When school resumed from vacation last week, officials said that while Diorio was not exactly missing, they had not heard from him since he left for a Florida vacation and did not know when he would ­return. The mystery deepened, speculation swirled.

On Wednesday, school officials finally broke their silence over the principal’s status, saying he had been placed on leave Dec. 18 pending an audit into the school’s finances. While they did not disclose Diorio’s whereabouts, school officials said he was cooperating with the inquiry.

“This leave is not disciplinary, and no conclusion has been reached regarding Mr. Diorio,” Superintendent Richard ­Langlois said in a statement. Auditors will look into the “management of certain financial and other affairs” at the high school, he said.

Through his office, Langlois declined to comment further. In the statement, he asked that the public refrain from “any speculation or conjecture” about the investigation.

A School Committee member, ­Arthur Grabowski, said that the audit will focus on a student activ­ities account at the school that has “been an issue for a long period of time.” He would not say whether officials suspect theft or fraud.

Grabowski acknowledged there has been “a lot of confusion” around Diorio’s absence, but said school board members have been limited in what they can say.

“Under advice of counsel, we’ve had to proceed very carefully,” he said. “We don’t want to taint the process. When the audit comes out, we’ll know more.”

The district attorney’s office said Wednesday that it is not ­involved in the investigation. Diorio could not be reached for comment.

Grabowski said he was frustrated by the “idiotic rumors” that have taken hold in recent days, saying many were unfair to Diorio.

“He wasn’t missing in a side-of-a-milk-carton kind of way,” he said. “People just went hogwild with this.”

But Steve Castinetti, vice chairman of the Board of ­Selectman, criticized school ­officials for failing to explain Diorio’s absence earlier, even to town leaders.

“We certainly should be brought into what’s going on, and I don’t know why we ­haven’t been,” he said. “I think the townspeople and taxpayers have a right to know what’s ­going on, especially those with children at the school.”

But Wendy Reed, chair­woman of the school board, said it is not the committee’s role to discuss personnel matters, even when it involves a principal. She said the superintendent told the board when Diorio was placed on leave, saying he would be “out for a while,” but they didn’t inquire further.

The town manager called for the audit, Reed said, adding that it was her understanding that Diorio has returned to the area and has met with the ­superintendent.

“This was blown way out of proportion,” she said. “There have been some awful rumors.”

The town manager, Scott Crabtree, could not be reached for comment Wednesday.

The audit comes on the heels of an investigation into town finances, which in August found that department heads made about $2 million in questionable purchases between June 2010 and March 2012. It also determined that a dozen public works projects did not comply with bidding laws.

Joey Aversa, a high school senior, said students were surprised when Diorio did not return when school resumed after vacation, but that teachers said they did not know where he was or when he would return.

The lack of information frustrated some students, who posted the fliers to draw attention to the matter.

“We shouldn’t have to go to school every day thinking ‘Where’s our principal,’” he said. “Who’s running the school? It doesn’t make sense.”

Reed urged patience, but cast doubt on whether Diorio would ever return to the school.

“Honestly, wouldn’t it be difficult to come back to this?” she asked. “People have already hung him in the square.”

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